func setHairpinMode(link netlink.Link, enable bool) error {
	err := netlink.LinkSetHairpin(link, enable)
	if err != nil && err != syscall.EINVAL {
		// If error is not EINVAL something else went wrong, bail out right away
		return fmt.Errorf("unable to set hairpin mode on %s via netlink: %v",
			link.Attrs().Name, err)
	}

	// Hairpin mode successfully set up
	if err == nil {
		return nil
	}

	// The netlink method failed with EINVAL which is probably because of an older
	// kernel. Try one more time via the sysfs method.
	path := filepath.Join("/sys/class/net", link.Attrs().Name, "brport/hairpin_mode")

	var val []byte
	if enable {
		val = []byte{'1', '\n'}
	} else {
		val = []byte{'0', '\n'}
	}

	if err := ioutil.WriteFile(path, val, 0644); err != nil {
		return fmt.Errorf("unable to set hairpin mode on %s via sysfs: %v", link.Attrs().Name, err)
	}

	return nil
}

func setupVeth(netns string, br *netlink.Bridge, ifName string, mtu int, hairpinMode bool) error {
	var hostVethName string

	err := ns.WithNetNSPath(netns, false, func(hostNS *os.File) error {
		// create the veth pair in the container and move host end into host netns
		hostVeth, _, err := ip.SetupVeth(ifName, mtu, hostNS)
		if err != nil {
			return err
		}

		hostVethName = hostVeth.Attrs().Name
		return nil
	})
	if err != nil {
		return err
	}

	// need to lookup hostVeth again as its index has changed during ns move
	hostVeth, err := netlink.LinkByName(hostVethName)
	if err != nil {
		return fmt.Errorf("failed to lookup %q: %v", hostVethName, err)
	}

	// connect host veth end to the bridge
	if err = netlink.LinkSetMaster(hostVeth, br); err != nil {
		return fmt.Errorf("failed to connect %q to bridge %v: %v", hostVethName, br.Attrs().Name, err)
	}

	// set hairpin mode
	if err = netlink.LinkSetHairpin(hostVeth, hairpinMode); err != nil {
		return fmt.Errorf("failed to setup hairpin mode for %v: %v", hostVethName, err)
	}

	return nil
}

// attach a container network interface to an external network
func (v *veth) attach(n *configs.Network) (err error) {
	brl, err := netlink.LinkByName(n.Bridge)
	if err != nil {
		return err
	}
	br, ok := brl.(*netlink.Bridge)
	if !ok {
		return fmt.Errorf("Wrong device type %T", brl)
	}
	host, err := netlink.LinkByName(n.HostInterfaceName)
	if err != nil {
		return err
	}

	if err := netlink.LinkSetMaster(host, br); err != nil {
		return err
	}
	if err := netlink.LinkSetMTU(host, n.Mtu); err != nil {
		return err
	}
	if n.HairpinMode {
		if err := netlink.LinkSetHairpin(host, true); err != nil {
			return err
		}
	}
	if err := netlink.LinkSetUp(host); err != nil {
		return err
	}

	return nil
}

//.........这里部分代码省略.........
	// Get the sandbox side pipe interface handler
	sbox, err := netlink.LinkByName(containerIfName)
	if err != nil {
		return err
	}
	defer func() {
		if err != nil {
			netlink.LinkDel(sbox)
		}
	}()

	n.Lock()
	config := n.config
	n.Unlock()

	// Add bridge inherited attributes to pipe interfaces
	if config.Mtu != 0 {
		err = netlink.LinkSetMTU(host, config.Mtu)
		if err != nil {
			return err
		}
		err = netlink.LinkSetMTU(sbox, config.Mtu)
		if err != nil {
			return err
		}
	}

	// Attach host side pipe interface into the bridge
	if err = addToBridge(hostIfName, config.BridgeName); err != nil {
		return fmt.Errorf("adding interface %s to bridge %s failed: %v", hostIfName, config.BridgeName, err)
	}

	if !config.EnableUserlandProxy {
		err = netlink.LinkSetHairpin(host, true)
		if err != nil {
			return err
		}
	}

	// v4 address for the sandbox side pipe interface
	ip4, err := ipAllocator.RequestIP(n.bridge.bridgeIPv4, nil)
	if err != nil {
		return err
	}
	ipv4Addr := &net.IPNet{IP: ip4, Mask: n.bridge.bridgeIPv4.Mask}

	// Down the interface before configuring mac address.
	if err := netlink.LinkSetDown(sbox); err != nil {
		return fmt.Errorf("could not set link down for container interface %s: %v", containerIfName, err)
	}

	// Set the sbox's MAC. If specified, use the one configured by user, otherwise generate one based on IP.
	mac := electMacAddress(epConfig, ip4)
	err = netlink.LinkSetHardwareAddr(sbox, mac)
	if err != nil {
		return fmt.Errorf("could not set mac address for container interface %s: %v", containerIfName, err)
	}
	endpoint.macAddress = mac

	// Up the host interface after finishing all netlink configuration
	if err := netlink.LinkSetUp(host); err != nil {
		return fmt.Errorf("could not set link up for host interface %s: %v", hostIfName, err)
	}

	// v6 address for the sandbox side pipe interface
	ipv6Addr = &net.IPNet{}

//.........这里部分代码省略.........
		}
	}()

	// Get the sandbox side pipe interface handler
	sbox, err := netlink.LinkByName(name2)
	if err != nil {
		return err
	}
	defer func() {
		if err != nil {
			netlink.LinkDel(sbox)
		}
	}()

	// Add bridge inherited attributes to pipe interfaces
	if config.Mtu != 0 {
		err = netlink.LinkSetMTU(host, config.Mtu)
		if err != nil {
			return err
		}
		err = netlink.LinkSetMTU(sbox, config.Mtu)
		if err != nil {
			return err
		}
	}

	// Attach host side pipe interface into the bridge
	if err = netlink.LinkSetMaster(host,
		&netlink.Bridge{LinkAttrs: netlink.LinkAttrs{Name: config.BridgeName}}); err != nil {
		return err
	}

	if !config.EnableUserlandProxy {
		err = netlink.LinkSetHairpin(host, true)
		if err != nil {
			return err
		}
	}

	// v4 address for the sandbox side pipe interface
	ip4, err := ipAllocator.RequestIP(n.bridge.bridgeIPv4, nil)
	if err != nil {
		return err
	}
	ipv4Addr := &net.IPNet{IP: ip4, Mask: n.bridge.bridgeIPv4.Mask}

	// Set the sbox's MAC. If specified, use the one configured by user, otherwise generate one based on IP.
	mac := electMacAddress(epConfig, ip4)
	err = netlink.LinkSetHardwareAddr(sbox, mac)
	if err != nil {
		return err
	}
	endpoint.macAddress = mac

	// v6 address for the sandbox side pipe interface
	ipv6Addr = &net.IPNet{}
	if config.EnableIPv6 {
		var ip6 net.IP

		network := n.bridge.bridgeIPv6
		if config.FixedCIDRv6 != nil {
			network = config.FixedCIDRv6
		}

		ones, _ := network.Mask.Size()
		if ones <= 80 {